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Well here she is boys. After 2 years of planning on building an AF build, I finally scored a chassis. A 2007 RMZ450 chassis. I scored this for a mere $500 bucks. Yes it isn't a CRF chassis or a newer (2013+) roller, but this will be a unique build none to less. I'm contemplating a 500AF build but I seen a RM250AF build and fell in love with it. Problem is that I already have a '15 TC250 so to have another 250 2t would be....a bad investment to say the least. I kinda want a RM125AF build but I already have a '03 CR125/134. So my last option, a CR/KX500 motor..
What do you guys think? What years for the CR500 motor? What about the KX500 motor? I plan on doing this build over the course of the Spring and maybe the Summer, just depends on the budget.
All input is greatly appreciated, thank you Vital members!!
What do you guys think? What years for the CR500 motor? What about the KX500 motor? I plan on doing this build over the course of the Spring and maybe the Summer, just depends on the budget.
All input is greatly appreciated, thank you Vital members!!
Ps, I've owned rm125, rm250 and rmz450.
I would look for a 500 smoker.
The Shop
I seen a RMZ AF conversion but with a YZ250 motor and a KX250 motor....but I'd rather stick with Suzuki to Suzuki (with the exception of the CR500 or KX500)
http://www.vitalmx.com/forums/Moto-Related,20/my-Rmz-200-sx-build,12632…
I see CR500 motors on eBay all the time, but hardly any KX500 motors
Gives you a Suzuki the Suzuki, and something a bit less common place than a CR/ KX500 AF. CR/ KX AFs are becoming like arseholes - everyone's got them. A 'finner' is the only sort of AF I'd ever build now - I've made far too many AFs since '97, to have much interest in them. Though, it can be a cheap way to get a modern(er) bike though, with so many noodles ruining 4t engines.....
Check out the YZF frame with a WR 500 engine a page or two back currently, in the 'Kick ass Two Strokes' thread.
The aluminium stock for an AF? - you can do it for much less than you think - it all comes down to finding suppliers. Even with a full cradle replacement, you are only looking at a few feet of tubing. Engine mounts - I'm a fan of RA sections, with a lovely radius inside the RA. You can get plenty of 6061 series RA. Materials cost, is bugger all. Weld beading, can amount to less than a couple of feet of bead. Just do it right - put the CS in the same place ( there are limits, due to variations in the distance from the SA pivot housing in the engine, to CS centre) as the original motor, so as not to stuff up the handling / suspension, and Not build to ancillaries convenience (so many AFs are done that way, and it's a bad way to do it) , and you'll have quite a bike.
07 rmz450 250af a friend of mine built last year, currently for sale
That's the link to his for sale ad, his contact info is there. I'm sure he wouldn't mind.
Why don't you drop a later model KTM 300 donk in it, stroke it out to 330 or something and have something unique and you can buy parts for.
1st thing is you cut the cradle out of the frame. Cut it right at the top of the “Y”
You will have to remove a bit more material later but this is the start.
2. You’ll have to make new bushings for the back of the motor – where the swing arm goes through. The Suz swing arm is a smaller diameter then the yam.. so you need make new ones.
3. You have to do step 2 first before you line up the motor from left to right so the counter shaft sprocket lines up with the rear sprocket. It’s easy to do once the bushing is the right size for the swing arm bold.
I put the motor on the bike and the swing arm bolt through it. Put on the rear wheel with sprocket and countershaft sprocket on the motor. Now, line up the rear wheel so that it’s straight (with the line marks on swing arm) and tightened the rear axle.
ii. Next take a piece of angle iron that is long enough to reach from the rear sprocket to the counter shaft sprocket. Clamp the angle iron with vice grips (or similar) onto the rear sprocket. Move the motor from left to right or right to left till the counter shaft sprocket touches that angle iron… thus giving you a straight line between the two sprockets. Then you will measure the spacer size required that slides onto the swing arm bolt between the motor and the swing arm that lines everything up…
So you have to make spacers to take up the slop between the motor and swing arm.. .but bushings must be made first.
This pic has the stock YZ bushing in the motor... you can see how they are too big for the suz swing arm bolt. So new bushings that fit are the first task so you can line up the motor/sprockets so the chain runs in a straight line.
Pit Row
Note: the YZ motor tilts back slightly. The cylinder is not vertical on the std YZ's. You'll want to put the pipe on it so you can mess with the angle you want it at when you weld up the front motor mounts. But figure out the back part of the motor (bushing and left to right sprocket alignment thing) first. Then it's just up and down with the motor.
Next trick will be the air boot. And, it took me sometime to figure this out. I was going to make a mold and make my own.... then I ran into this idea while in the plumbing section of a local hardware store.
The RMZ (and all 4 stroke) boots are too small to fit on the bell of the 2 stroke carb and they come up a little short.. The solution is to go to the hardware store and for 5 - 8 bucks you can buy a 2" piece of hose for fixing pipes. It slides right over the top of the stock boot (after you sand off the ridge on it for the stock hose clamp) and you can custom make it to the length you need. It fit right over the 2 stroke carb too.. Simple slick solution. Then hose clamp/ silicon or weather strip adhesive the 2" extension onto the stock boot.
Now, inside the stock boot - where the 4 stroke carb bell would sit - you'll have to make something out of plastic or metal to allow you to put clamping force on the outside without crushing the stock boot. I found a piece of PVC pipe in the same hardware plumbing section that fit inside it. Cleaned it up with a dremel tool and sand paper to make it look like a velocity stack... Silicone it in place... slide the 2" rubber hose over the top... silicone it in place... put a hose clamp on it and problem cleanly and cheaply solved.
Sorry I don’t have a pic of what I did inside the boot as it’s on the bike. But it worked very well and solved a major issue with these builds.
Actually - if you zoom in on the top air boot photo you can see a bit of the white PVC pipe I used inside as mentioned.
So there you go... )
Plug weld the joint by the front of the engine.. put a lug of solid AL in there too... use sheet metal screws to fix stuff in place then weld up.. pull sheet metal screws and weld up the holes left by them.
You want your cases and crank all polished up too... )
One last thing... the shock linkage.. WAY too stiff on this bike for a 2 stroke engine. I built this for off road use... I got a devol link (the adjustable one) for the rear. Made a big difference. I valved the shock and fork really light to try and get it to work but it didn't come around till I put on the devol link in the rear.
I weigh 180 lbs and put in a 40 kg fork spring and a 4.6 kg rear... which seems to light but it didn't work till I went light.
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